The present invention relates to a torque fuse device for connecting two axially aligned shafts. More particularly, the torque fuse device includes a bi-directional torque release mechanism that releases the torque carrying capability of the shafts when a predetermined release torque is exceeded.
The use of torque release mechanisms to couple two axially aligned shafts is well known and used in a variety of different fields. For example, torque release mechanisms may be used in rolling steel mills and in watercraft drive applications. Specifically, torque overloads or spikes commonly occur when the steel mill rolls become jammed or when a propeller on a vessel strikes an object when traveling through a body of water. In either case, the torque release mechanism operates to release the connection between the two shafts when the aforementioned torque overload events occur to reduce or eliminate damage to the axially aligned shafts.
One type of torque release mechanism that may be used in either of these applications is referred to as a shear pin coupler. In this arrangement, a break pin is fastened between two flanges that extend from opposing axially aligned shafts. The break pin includes a weakened area that is positioned transverse to the longitudinal axis of the pin, which allows the pin to break at a predetermined loading point. Therefore, when a torque overload occurs, the pin breaks and the two shafts are permitted to move relative to each other.
Another known torque release mechanism utilizes friction to couple the shafts to one another. For example, U.S. Pat. No. 5,051,018 provides a coupling for coupling two mutually coaxial rotatable parts. The coupling includes a cylindrical bladder that is adapted to be filled with fluid so that it expands thereby frictionally engaging the two shafts. When the bladder to filled to a desirable level to achieve the necessary friction between the shafts, a plug is used top seal the fluid within the bladder. When a torque overload condition occurs, a blade cuts or otherwise removes the plug to release the hydraulic fluid from the bladder. The friction between the shafts is then reduced allowing the two shafts to move relative to one another.
While each of the torque release mechanisms described above operates to disengage the torque carrying capability between the external shafts, they each suffer from a number of drawbacks and deficiencies. For instance, the use of a break pin or temporary plug will force the user to replace the pin or plug each time the device is reset, which is time consuming and inefficient. In addition, the user must purchase and store replacement parts, which in turn increases the operational cost of the aforementioned devices. Further, the break pin may be subject to various vibratory loads within the connected machinery during operation. This repeated vibratory loading often times causes the break pins to fail prematurely, which results in an unintended shutdown of the equipment.
Some prior art devices will attempt to self-reset with each rotation after a torque overload has occurred. Specifically, the self-resetting devices reset by the rotation of a pair of fuse halves into a particular position where a tooth engages a hole or slot. However, the use of self-resetting devices may also be problematic. Each time the self-resetting device attempts to reset, a vibratory load is imposed on one or more of its components. Thus, if the machinery continues to rotate after a torque release has occurred, the self-resetting device may destroy itself due to is own vibratory loading.
Accordingly, there exists a need for a torque release mechanism that ameliorates the aforementioned drawbacks and deficiencies. The present invention fills these needs as well as other needs.